The pot I first noticed this on wasn't an expensive unglazed pot, I got it
from Dallas Bonsai If I remember right... anyway I would not have noticed
the coating except for a defect, a run in the "slip glaze" it was very hard
but I managed to chip it off, after looking closely I believe every brown
pot I have seen has this exact same coating. I imagine it is to water proof
the clay so it can survive freezes. Perhaps similar to the frost free
coating European terra cotta planters some times have on them.

Anyway it seems by consensus that a pot must be sealed to prevent cracking
during winter. Thanks for the info.


Kevin.


----- Original Message -----
From: "Bart Thomas"
To:
Sent: Wednesday, May 26, 2004 4:39 PM
Subject: [IBC] Ceramic Pots


----- Original Message -----
From: "Alan Walker"

I don't know where your pots come from, but I have never noticed
such a coating on unglazed Tokoname bonsai pots.
Alan Walker

I had a large high grade unglazed japanese pot have parts of the surface
flake off this winter. It came off just as though it were heavy paint on a
poorly prepared surface. This was not a new pot, but one which had come
through at least 5 winters (zone 6) unscathed.

Until it came off (in parts) it had not appeared to be any sort of coating
whatever. The finish under the "coating" seemed much rougher than the
original finish on the pot.

FWIW, we plan to do some experimental sand-blasting on it, to see what
happens.

Regards,

Bart


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